After 21 months on the picket line, unionized Guenther & Son Inc. flour mill workers said they called off their strike to be able to vote on the next contract.

The current contract expires April 30. The union on Tuesday offered to return its members to work.

“We felt like we should take the fight inside with the law the way it is and the contract coming up,” said Frank Perkins, president of Teamsters Local 657, which represents the workers. “The guys didn't give up.”

Steve Phillips, a senior vice president for the company best known for Pioneer-brand flour and baking mixes, said the union “made an unconditional offer to return.” That means the rank-and-file agreed to return without winning concessions.

What's also in dispute now is whether their jobs are still there.

Employers are not required to take workers back after a wage strike, and Guenther brought in replacement workers.

“We permanently replaced the folks who are out on economic strike,” Phillips said.

He said negotiations were now about who could be brought back for the plant's “handful” of openings — four or five.

The union initially said about 90 workers went on strike, but Phillips put the number at about 75, in part because some workers resigned or retired.

Perkins, meanwhile, contended the workers “have a contractual right to return.”

The strike began in April 2011 to protest a contract that would have resulted in smaller paychecks due to rising health insurance premiums.

The parties entered a three-year contract in April 2010 but reopened it a year ago later to negotiate the final two years. The company offered a 50-cent hourly pay increase but proposed hiking family medical insurance premiums to $35 a week from $11 a week. That meant workers would have seen $4 less each week in their paychecks.

Neither side budged as the strike stretched on, leaving the workers picketing the mill near South Alamo and Probandt streets without paychecks or medical insurance.

Efforts to reach an agreement with a federal mediator failed.

Things got ugly early on, with each side alleging unlawful surveillance by the other. The National Labor Relations Board “found merit” with both sides' complaints, and the matter was settled.